1. Field of the Invention
The present invention relates to a system and a method for inspection of chips, and more particularly, to a system and a method for inspection of chips on a tray.
2. Description of the Related Art
As the chip on glass (COG) packaging technique becomes more and more popular, the demand for the inspection of COG chips is quickly rising. In addition to the wafer level inspection, chips placed on a tray must be inspected before they are installed on a display panel to increase production yield or minimize the risk of repair or rework operation. In order to meet such inspection requirement, several inspection systems for inspecting chips on a tray are currently in use.
Generally, trays for receiving chips are available in sizes of 2, 3, and 4 inches. To handle this variety in tray size, complicated adjustment mechanisms have been developed for the tray-handling devices so that the tray-handling devices can be adjusted to fit the size of the trays. However, the adjustment of the tray-handling devices usually requires a significant amount time, which increases the downtime of the system. In addition, any adjustment incurs risk of damaging processing products by making an adjustment that is beyond safe limits.
An imaging sensor is usually utilized in inspection systems for detecting defects in chips on a tray. The imaging sensor is focused on the surface of a chip being inspected, and then performs the detection operation. However, in traditional inspection systems, chip detection operation is easily obstructed by the vibration caused by driving devices. The COG chips are tiny and light, and normally are loosely disposed on a tray. Therefore, vibration may cause the chips to move during inspection, resulting in difficulties in performing accurate inspection.
After inspection, defective chips are replaced with good chips in some inspection systems. In such systems, the defective chips are removed from a tray, and good chips are then placed in empty recesses on the tray. Usually, the systems use a pickup head to remove defective chips and place good chips on the tray. A single pickup head may easily become the source of cross-contamination. Moreover, the process of replacing defective chips with good chips is slow, resulting in high inspection cost.
In summary, traditional inspection systems for chips on a tray have many disadvantages, and a new inspection system without the above disadvantages is required.